It is well known in the art of drawing circumferences, the drawing compass comprising at least two articulated arms, one arm having a sharp pin for puncturing the sheet of paper on which the drawing is made, and the other arm having an end with a graphite for drawing the circle. Anyone who has used this drawing tool knows about its inconveniences insofar as to the damages done on the drawing and particularly in the sheet of paper.
There are also many drawing plates having a plurality of cut-out circles having different diameters so as the draftsman may draw a circumference by inserting the pen in the selected cut-out circle and running the tip of a pen around the periphery of the cut-out circle. The cut-out circles have different diameters the values of which are indicated on the plate.
In order to have a convenient variety of circle sizes, the plate must have a large size to include all the necessary circle diameters. Otherwise, many drawing plates are necessary for containing at least the most usual diameter sizes.